You will then need to locate the saved iOS 5.1.1 SHSH blobs. Either you should have it on your computer or on Cydia. If it’s on your computer, simply place it in the same folder as the 5.1.1 IPSW file. If it’s on Cydia then just go ahead with the instructions.
Place your device in the DFU mode.
Open RedSn0w, click on extras, then SHSH blobs and then stitch.
Downgrade iOS 6 to iOS 5.1.1 with Redsn0w
Click IPSW and select the iOS 5.1.1 IPSW for your device.
iOS 6.0 to iOS 5.1.1 Downgrade
If you have your blobs on Cydia, click Cydia in the blobs section, otherwise click on local and select the SHSH blobs for iOS 5.1.1 for the device.
RedSn0w will now stitch them to create a firmware file for iOS 5.1.1. This firmware file can then be used to downgrade even if Apple is has stopped singing iOS 5.1.1.
Redsn0w Stitch SHSH blobs to Downgrade iOS 6.0.1 to 5.1.1
Go back two pages in RedSn0w and click on Pwned DFU; this will place your device in Pwned DFU so that iTunes can restore using the stitched firmware. Skipping this will give you the 1600 error in iTunes.
Pwned DFU Redsn0w iOS 6 to 5.1.1
Open iTunes. Your device should be detected in recovery mode. Hold option and click restore. After that select your stitched firmware file. The filename should have a prefix of 13 numbers which is basically your device’s ECID.
Let iTunes completely restore your device, and if you get an ‘error – 1’, don’t worry that’s normal.
iOS 6 downgrade to iOS 5.1.1 iTunes erroer -1
Now open RedSn0w go to extras and click on recovery fix.
Place your device into DFU mode again and the recovery fix should run.
Once the recovery fix is done the device will be restored to iOS 5.1.1.
Follow these steps just the way as they are told, and don’t go about trying this if you don’t have all the prerequisites. Once again you need the following; an A4 device, saved SHSH blobs, Redsn0W and the IPSW 5.1.1 firmware file for your device. Feel free to ask any questions in the comment section below.